fix: #929 raises on JPEG with image/jpg MIME-type

At least one client, perhaps Adobe PDF Converter, produces a PPTX with
JPEG images mapped to the non-existent `image/jpg` MIME-type rather than
the correct `image/jpeg`.

Accept `image/jpg` as an alias for `image/jpeg`, which is consistent
with the behavior of PowerPoint which loads these files without
complaint.

HISTORY.rst

@@ -3,13 +3,15 @@
 Release History
 ---------------
 
-0.6.24-dev3
+0.6.24-dev4
 +++++++++++++++++++
 
+- fix: #929 raises on JPEG with image/jpg MIME-type
 - fix: #943 remove mention of a Px Length subtype
 - fix: #972 next-slide-id fails in rare cases
 - fix: #990 do not require strict timestamps for Zip
 
+
 0.6.23 (2023-11-02)
 +++++++++++++++++++
 

features/prs-open-save.feature

@@ -33,3 +33,7 @@ Feature: Round-trip a presentation
       When I save and reload the presentation
       Then the external relationships are still there
        And the package has the expected number of .rels parts
+
+  Scenario: Load presentation with invalid image/jpg MIME-type
+     Given a presentation with an image/jpg MIME-type
+      Then I can access the JPEG image

features/steps/presentation.py

@@ -5,6 +5,7 @@
 import io
 import os
 import zipfile
+from typing import TYPE_CHECKING, cast
 
 from behave import given, then, when
 from behave.runner import Context
@@ -14,6 +15,10 @@
 from pptx.opc.constants import RELATIONSHIP_TYPE as RT
 from pptx.util import Inches
 
+if TYPE_CHECKING:
+    from pptx import presentation
+    from pptx.shapes.picture import Picture
+
 # given ===================================================
 
 
@@ -38,6 +43,11 @@ def given_a_presentation_having_no_notes_master(context: Context):
     context.prs = Presentation(test_pptx("prs-properties"))
 
 
+@given("a presentation with an image/jpg MIME-type")
+def given_prs_with_image_jpg_MIME_type(context):
+    context.prs = Presentation(test_pptx("test-image-jpg-mime"))
+
+
 @given("a presentation with external relationships")
 def given_prs_with_ext_rels(context: Context):
     context.prs = Presentation(test_pptx("ext-rels"))
@@ -189,6 +199,17 @@ def then_the_package_has_the_expected_number_of_rels_parts(context: Context):
     assert member_count == 18, "expected 18, got %d" % member_count
 
 
+@then("I can access the JPEG image")
+def then_I_can_access_the_JPEG_image(context):
+    prs = cast("presentation.Presentation", context.prs)
+    slide = prs.slides[0]
+    picture = cast("Picture", slide.shapes[0])
+    try:
+        picture.image
+    except AttributeError:
+        raise AssertionError("JPEG image not recognized")
+
+
 @then("the slide height matches the new value")
 def then_slide_height_matches_new_value(context: Context):
     presentation = context.presentation

src/pptx/__init__.py

@@ -25,7 +25,7 @@
 if TYPE_CHECKING:
     from pptx.opc.package import Part
 
-__version__ = "0.6.24-dev3"
+__version__ = "0.6.24-dev4"
 
 sys.modules["pptx.exceptions"] = exceptions
 del sys
@@ -62,6 +62,8 @@
     CT.VIDEO: MediaPart,
     CT.WMV: MediaPart,
     CT.X_MS_VIDEO: MediaPart,
+    # -- accommodate "image/jpg" as an alias for "image/jpeg" --
+    "image/jpg": ImagePart,
 }
 
 PartFactory.part_type_for.update(content_type_to_part_class_map)